As disclosed by U.S. Pat. No. 4,822,398 McMaster et al, glass sheets have previously been bent between a pair of opposed bending platens whose movement between flat and bent shapes during cyclical operation is provided by a plurality of actuators connected to the platens. The platens are arranged in lower and upper positions with both platens provided with wheels that engage the glass sheet during the bending while the glass sheet is continually conveyed back and forth in order to reduce marking and distortion. After the bending, quench tubes that are part of the platens supply quenching gas that provides tempering or heat strengthening of the bent glass sheet.
U.S. Pat. No. 4,881,962 Reunamaki et al discloses bending and tempering of glass sheets wherein a roller conveyor is moved from a flat shape to a curved shape having an axis of curvature transverse to the direction of conveyance to provide bending of a glass sheet being conveyed thereby under the actuation of cylinders. A linkage that connects the cylinders has all of its links pivotable about the axes transverse to the direction of the conveyance. As such, the bending is controlled by the extent to which the cylinders are extended and retracted during each cycle of operation.